1. Field of Invention
The present invention relates to an illuminating device. More particularly, the present invention relates to an optical module and a double-sided light-emitting lamp.
2. Description of Related Art
Lamps become more diversified to meet market requirements. One of conventional lamps is a hanging transparent lamp which can emit light beam toward the ceiling and the ground simultaneously, so as to achieve better appearance and illumination. In addition, to meet actual applications, the quantity of downward emitted light is generally greater than that of upward emitted light.
For adjusting a ratio between the quantity of downward emitted light and that of upward emitted light, a conventional method is to deposit a metal film on another transparent plate surface of a lamp by evaporation. However, when being applied on a transparent plate with a large area, such method causes manufacture cost to be increased, and thus is not cost-effective to manufactures. Furthermore, after the metal film is deposited on the transparent plate surface, at least 10% of the light flux is absorbed, thus resulting in optical loss.
Hence, there is need to provide a lamp which can adjust the light-emitting quantity and decrease optical loss to overcome the aforementioned problems.